What is the reason for the headlights not working and the horn not sounding?
4 Answers
Car headlights not working and horn not sounding reasons and solutions are as follows: The reason for car headlights not working and horn not sounding: If the car's lights and horn are both not working or sounding, it is generally due to a blown fuse or a damaged converter. The solution for car headlights not working and horn not sounding: Check if the converter's fuse is blown. If the fuse is not blown, use a multimeter to measure the converter's output voltage. If there is a 12v output, if it exceeds or there is no output, it proves the converter is damaged, and it only needs to be replaced. After replacement, if you find that the headlights can be turned on but the horn does not sound or the sound is weak, it may be due to a ground wire break, and you need to locate and reconnect the broken position.
Driving trucks for over 20 years, I've seen all kinds of electrical failures. When headlights and horn fail simultaneously, it's usually a power supply issue. Just last week, my own vehicle had this problem - it started normally but both functions were dead. I immediately checked the battery voltage with a multimeter - over 12 volts meant the battery was fine. Then I went straight to the fuse box, located the main power fuse, pulled it out and sure enough, it was blown. Replaced it with a spare 20-amp fuse and everything worked again immediately. If the fuse is intact, you'll need to check the combination switch assembly under the steering wheel, which controls both the headlight switch and horn button. Loose body ground connections can also cause this - just tighten the ground screw with a wrench. Remember, if this happens at night, turn on hazard lights and pull over safely - nothing's more important than safety.
Buddy, I've encountered this situation before. When the headlights don't work and the horn won't sound, it's likely a shared circuit issue. Don't panic yet. Pop the hood and check if the battery terminals are corroded or loose. If there's poor contact, clean them thoroughly and retighten. Then inspect the fuse box – most vehicles have separate fuses for turn signals and horn, but a blown main power fuse could affect both simultaneously. Refer to your owner's manual to locate the corresponding positions, use fuse pullers to remove and check if the filaments are broken. Replacing a fuse costs less than ten bucks – super economical. If it still doesn't work after replacement, the problem might be with the combination switch assembly, which requires professional repair. Remember to disconnect the battery by removing the key before any operations.
The apprentice manual states that when both headlights and horn fail simultaneously, the first step is to inspect the common circuit. First, use a multimeter to check if the battery voltage is normal to rule out the possibility of a dead battery. Second, inspect the condition of the main fuse and branch fuses, especially those labeled HEAD and HORN in the fuse box under the driver's seat. Third, test the combination switch, as this assembly under the steering wheel controls both the lights and the horn. Finally, check the relay's operational status and whether the body ground wire is oxidized or loose. The master taught us that in such situations, we must stop the vehicle immediately—driving without lighting and warning functions is extremely dangerous, especially during nighttime driving.
